Note: Descriptions are shown in the official language in which they were submitted.
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33,230-00
AQUEOUS SPRAY COMPOSITIONS
BACKGROUND OF THE INVENTION
Aqueous spray compositions have been used for several decades to
apply agricultural compounds. However, the results obtained from aqueous
spray compositions are not entirely satisfactory because spray drift may
occur. Spray drift is especially undesirable because under/over application of
agricultural compounds may occur. In addition, spray drift may contaminate
non-target areas with unacceptable levels of agricultural compounds.
In recent years, the potential for drift from agricultural spray applica-
tions has become a matter of intensive study. One result of that study is the
identification of spray droplet size as one of the most important factors
to contributing to drift. High molecular weight, water-soluble polymers are
currently added to spray compositions to increase droplet size and thereby
reduce drift. However, high molecular weight, water-soluble polymers are not
entirely satisfactory because they are expensive to use at the concentrations
required to substantially increase droplet size.
SUMMARY OF THE INVENTION
The present invention provides an aqueous spray composition
comprising about 0.0005 to 1 wt/wt% of a water-soluble polymer and at least
about 0.05 wt/wt% of a surfactant selected from the group consisting of a
2 o sulfonated surfactant, a sulfated surtactant and mixtures thereof,
provided
that the surfactant has at least one straight or branched carbon chain
containing at least nine carbon atoms. Preferably, said polymer is selected
from the group consisting of a polyethylene oxide), a poiy(vinyl alcohol), a
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polyvinyl pyrrolidone), a polyvinyl ether), a cellulose
ether, and mixtures thereof.
The present invention further provides a method
for reducing the spray drift of an aqueous spray composition
and a method for increasing the median diameter of spray
droplets.
Advantageously, the present invention provides
aqueous spray compositions which exhibit a reduced potential
for spray drift when compared to spray compositions
containing conventional spray drift control additives such
as high molecular weight, water-soluble polymers. The
aqueous spray compositions of the present invention
preferably contain about 0.005 to 0.05 wt/wt~ of the
polymer, and about 0.05 to 1 wt/wto of the surfactant.
The present invention provides an aqueous spray
composition having increased droplet size and exhibiting
reduced spray drift potential. The present invention also
provides a method for increasing the mean droplet diameter
of an aqueous spray composition, and to reduce the spray
drift potential thereof.
In a composition aspect, the invention provides an
aqueous spray composition having a plurality of spray
droplets with a median diameter, for applying about 0.001 to
50 wt/wt~ of a pesticide, the improvement comprising adding
about 0.001 to 1 wt/wto of a water-soluble polyethylene
oxide) having a molecular weight greater than about
5x105 Daltons, and at least about 0.05 wt/wt~ of a surfactant
selected from the group consisting of a sulfonated
surfactant, a sulfated surfactant and mixtures thereof,
provided that the surfactant has at least one straight or
branched carbon chain containing at least nine carbon atoms,
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wherein, for a given spray apparatus, application, and
conditions, and based on the water-soluble polyethylene
oxide) and surfactant, the median diameter of the plurality
of spray droplets is increased above that of an aqueous
spray composition without said water-soluble polyethylene
oxide) and surfactant.
In a method aspect, the invention provides a
method for increasing the median diameter of spray droplets
and reducing the spray drift of an aqueous spray
composition, for applying about 0.001 to 50 wt/wt% of a
pesticide, the improvement to the method comprising adding
to the aqueous spray composition about 0.001 to 1 wt/wt% of
a water-soluble polyethylene oxide) having a molecular
weight greater than about 5x105 Daltons, and at least about
0.05 wt/wt% of a surfactant selected from the group
consisting of a sulfonated surfactant, a sulfated surfactant
and mixtures thereof, provided that the surfactant has at
least one straight or branched carbon chain containing at
least nine carbon atoms, wherein, for a given spray
apparatus, application, and conditions, and based on the
water-soluble polyethylene oxide) and surfactant, the
median diameter of the plurality of spray droplets is
increased above that of an aqueous spray composition without
said water-soluble polyethylene oxide) and surfactant.
Other aspects of the present invention will be
apparent to those skilled in the art from the following
disclosures.
DETAILED DESCRIPTION OF THE INVENTION
In one preferred embodiment of the present
invention, from about 0.0005 to about 1 wt% of a water-
soluble polymer and from about 0.05 to about 1 wt% of a
sulfonated or sulfated surfactant are added to an aqueous
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spray composition containing an agricultural compound; e.g.,
a herbicide to form an aqueous spray composition of the
present invention.
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It has been found that the median diameters of spray droplets are
dramatically increased when the polymer and surfactant of this invention are
present in aqueous spray compositions. The larger droplets are less prone to
spray drift.
The combination of surfactant and polymer in the present invention is
important in providing significantly increased droplet size and reduced spray
drift potential. The water-soluble polymer and surfactant of the present
invention are believed to associate or complex with one another in the aqueous
composition, promoting larger droplet sizes. These larger droplets tend to
drift
less when sprayed, allowing the composition to be more precisely applied
where needed.
Generally, it has been found that at least about 0.05% surfactant and
about 0.0005% polymer by weight are needed to provide the advantageous
droplet size enhancement of the present invention. The precise amount
required will vary depending on the other elements of the composition, the
choice of polymer and the choice of surfactant. Increasing the percentage of
the surfactant and/or polymer further increases droplet size. The exact
percentages that are best for a given composition can readily be determined by
one of skill in the art, and will be dependent on the desired median diameter
of
2 o the spray droplet.
The optimum droplet size depends on the application for which the
composition is used. If droplets are too large, there will be less coverage by
the
spray; i.e, large droplets will land in certain areas while areas inbetween
will
receive little or no spray composition. The maximum acceptable droplet size
2 5 may depend on the amount of composition being applied per unit area and
the
need for uniformity in spray coverage. Smaller droplets provide more even
coverage, but are more prone to drift during spraying. If it is particularly
windy
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during spraying, larger droplets may be preferred, whereas on a calmer day
smaller droplets may be preferred.
The spray droplet size may also depend on the spray apparatus; e.g.,
nozzle size and configuration. One skilled in the art will readily be able to
adjust the percentage of surfactant and/or polymer in the composition to
provide the desired droplet size for a given apparatus, application, and
conditions.
Preferred polymers of the present invention include polyethylene
oxide) polymers, polyvinyl alcohol) polymers, polyvinyl pyrrolidone)
1 o polymers, polyvinyl ether) polymers, and cellulose ether polymers all
having
molecular weights greater than about 2 x 105 Daltons. Polyethylene oxide)
polymers having a molecular weight of greater than about 5 x 105 Daltons are
more preferred with polyethylene oxide) polymers having a molecular weight
of about 1 x 106 to 1 x 10' Daltons being most preferred.
The surfactant is an especially important element of the present
invention and is present in at least about 0.05 wt/wt%. Surfactants suitable
for
use in the present invention include a-olefin sulfonates, alkylaryl sulfonic
acids and salts, alkyl sulfates, a-olefin sulfates, ethoxylated alcohol
sulfates,
and ethoxylated alkylphenol sulfates, all having at least one straight or
2 o branched carbon chain containing at least nine carbon atoms. The carbon
chain length is important to promote increased droplet size and reduced spray
drift potential.
Surfactants which are preferred for use in this invention include a-(C9-
C~8)olefin sulfonates such as an a-(C~4-C~6)olefin sulfonate,
2s C9-C~8alkylbenzene sulfonic acids and salts such as dodecylbenzene sulfonic
acid, sodium dodecyl benzene sulfonate and triethanolamine dodecyl
benzene sulfonate, C9-C~salkyl sulfates such as sodium decyl sulfate and
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sodium dodecyl sulfate, a-(C9-C~a)olefin sulfates such as an a-(C~4-C~6)olefin
sulfate, ethoxylated C9-C~$alcohol sulfates such as sodium dodecyl alcohol
(ethoxylate-3) sulfate and sodium tridecyl alcohol (ethoxylate-3) sulfate, and
ethoxylated C9-C~salkylphenol sulfates such as an ethoxylated nonylphenol
s sulfate.
The compositions of the present invention are useful for the application
of agricultural compounds such as pesticides, plant growth regulators,
safeners, and mixtures thereof. In particular, the compositions of this
invention are especially useful for the application of pesticides such as
to herbicides, insecticides, fungicides, nematicides, and molluscicides. In
general, the agricultural compound is present in the spray compositions of
this invention in an amount up to about 50 wt/wt% and is preferably present in
an amount from about 0.001 to 50 wt/wt%. The amount of agricultural
compound present in the compositions of this invention will depend on a
variety of factors such as spray volume, application rate and application mode
(for example, aerial vs. tractor application).
The present invention also provides a method greasing the
median diameter of spray droplets and reducing the spray drift of an aqueous
spray composition which comprises adding to the composition about 0.0005
2 o to 1 wt/wt% of a polymer of this invention and at least about 0.05 wt/wt%
of a
surfactant of this invention. Advantageously, the polymer and surfactant may
be added to the composition in the field prior to spraying or, in the case of
a
ready to use composition, may be added during the manufacture of the
composition.
2 s In one embodiment the aqueous spray compositions of this invention
containing an agricultural compound may be prepared by mixing together (1 )
a concentrate composition containing the agricultural compound, (2) a
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sufficient amount of the polymer, (3) a sufficient amount of the surfactant,
and
(4) water. Additional additives such as antifoam agents, dyes, preservatives
and the like may be added to the spray compositions of the present invention.
In order to facilitate a further understanding of the invention, the
s following example is presented primarily for the purpose of illustrating
more
specific details thereof. The invention should not be deemed limited thereby
except as defined in the claims.
EXAMPLE 1
1 o Evaluation of median droplet diameter of various~ol~eth~ lene
oxideJllsurfactant compositions
Aqueous spray compositions are prepared by dissolving 0.15 wtlwt%
of sodium dodecylbenzene sulfonate and various amounts of polyethylene
15 oxide) resins in deionized water. Comparative compositions (no surfactant)
are prepared by dissolving various amounts of polyethylene oxide) resins in
deionized water. The compositions are then sprayed through a Teejet 8001
flat fan nozzle (Spraying Systems Co.) at 40 psi using an air pressurized
reservoir. The beam of a Malvern Mastersizer particle sizer (Malvern
2 o Instrument Company) is positioned 12.5 cm below the spray nozzle and the
median diameters of the droplets are determined. The results are reported in
Tables I, II and III.
As can be seen from the data in Tables I, II and III, the median droplet
diameters produced by the aqueous spray compositions of the present
2s invention are significantly greater than the median droplet diameters
produced by the comparative compositions at the same concentration of
polyethylene oxide) resin.
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TABLE I
Median droplet diameter of various
POLYOX°N-12K' solutions
POLYOXN-12K Median Drop let Diameter~m~
Concentration 0.15 wtlwt%
wtlwt no NaDDBS NaDDBS2 added
0 142 127
0.0005 149 150
0.001 153 168
0.00125 155 -
0.0025 175 458
0.005 193 850
0.01 214 >1,000
0.02 300 >1,000
0.04 452 -
-= no evaluation
' A water-soluble polyethylene oxide) resin having an approximate molecular
weight of 1 x 106 Daltons, manufactured by Union Carbide Corporation,
to Danbury, CT.
2 sodium dodecylbenzene sulfonate
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TABLE II
Median droplet diameter of various
POLYOX°N-60K~ solutions
POLYOXN-60K Median Drop let Diameter (um~
Concentration 0.15 wtlwt%
wtlwt no NaDDBS NaDDBSz added
0 142 127
0.0005 - 247
0.001 174 401
0.00125 - 552
0.0025 216 >1,000
0.005 268 -
0.01 408 -
0.02 713 -
= no evaluation
' A water-soluble polyethylene oxide) resin having an approximate molecular
weight of 2 x 106 Daltons, manufactured by Union Carbide Corporation,
1 o Danbury, CT.
2 sodium dodecylbenzene sulfonate
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TABLE III
Median droplet diameter of various
POLYOX°Coagulant' solutions
POLYOXCoagulant Median Drop let Diameter ~m~
Concentration 0.15 wtlwt%
wtlwt no NaDDBS NaDDBS2 added
0 142 127
0.0005 178 358
0.001 - 750
0.00125 228 > 1, 000
0.0025 312 > 1, 000
0.005 508 -
0.01 >1,000 -
s -= no evaluation
' A water-soluble polyethylene oxide) resin having an approximate molecular
weight of 5 x 106 Daltons, manufactured by Union Carbide Corporation,
Danbury, CT.
l 0 2 sodium dodecylbenzene sulfonate
Although the compositions of the present invention have been illustrated
and described herein in terms of compositions comprising an agricultural
compound, the present invention is not limited to such compositions, but
15 encompasses all the subject matter within the scope of the appended claims
